Early Cretaceous Freshwater Fish Fauna in Kyushu, Japan

Early Cretaceous Freshwater Fish Fauna in Kyushu, Japan 247
In Palaeogene, the only record of a freshwater fish is a cypriniform fish from the
Eocene Horokabetsu Formation of the Ishikari Series in Yubari City, Hokkaido
(Inoue and Uyeno, 1968).
Freshwater fish fossils become abundant in the Neogene sediments. Fish fossils
from Iki Island in Nagasaki Prefecture are composed of 12 species of the order
Cypriniformes, 4 species of the Perciformes, one species of the Scorpaeniformes and
one species of the Mastacembelidae (Hayashi, 1975; Jordan, 1919; Uyeno, 1980).
Extant species of the Mastacembelidae is distributed in tropical Africa through Syria
to the Malayan Archipelago and China, but they are not distributed in Japan.
Besides these, several Miocene freshwater fishes have been found in Yamagata,
Kyoto, Gifu and Mie Prefectures. Most of them belong to the order Cypriniformes.
In Pliocene, numerous isolated pharyngeal teeth of cyprinid fishes are found
from the Kobiwako Group in Mie Prefecture (Nakajima, 1987). Gobiid fish,
Rhinogobius giurinus, are found from the Togo Formation in Kagoshima Prefecture
(Uyeno and Iwao, 1975).
The Pleistocene fishes are abundant in the Kusu Formation. They are consti
tuted of one salmonid, 3 cyprinids and 2 gobiids (Uyeno et al., 1975; Yabumoto,
1987). Numerous isolated pharyngeal teeth of Cypriniformes are found in the
Kobiwako Group (Nakajima, 1987). The cyprinid fish, Tribolodon sp. cf. T.
hakonensis, is described from the early or middle Pleistocene Shiobara Group in
Tochigi Prefecture (Uyeno, 1967). Several species of cyprinid fishes are found from
the Kusu Basin in Oita Prefecture (Nakajima et al., 1988).
In general, freshwater fish fossils are rare in the Mesozoic and Palaeogene
sediments, but became abundant in Neogene sediments in Japan. The Wakino fish
fauna represents the only significant Mesozoic freshwater fish fauna found so far in
Japan.
Acknowledgments
The present study is my doctoral dissertation that was submitted to the Faculty
of Science of Kyushu University in 1992. I wish to express my sincere gratitude to
Dr. Masamichi Ota, director of the Kitakyushu Museum and Institute of Natural
History (the former name is the Kitakyushu Museum of Natural History) and Dr.
Juichi Yanagida of Kyushu University, for valuable advice, guidance and encourage
ment throughout the present study. Dr. M. Ota helped me with the geological
investigation of the Wakino Subgroup and taught me much about geology and
paleontology. I am also grateful to the late Dr. Ryuzo Toriyama, the first director
of the Kitakyushu Museum and Institute of Natural History, for supporting and
encouraging my fish fossil studies. I benefited greatly from his library in the
Museum.
Dr. Teruya Uyeno of the National Science Museum, Tokyo, has guided and